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clantp

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NAME
CLANTP - return the value of the one norm, or the Frobenius
norm, or the infinity norm, or the element of largest abso-
lute value of a triangular matrix A, supplied in packed form

SYNOPSIS
REAL FUNCTION CLANTP( NORM, UPLO, DIAG, N, AP, WORK )

CHARACTER DIAG, NORM, UPLO

INTEGER   N

REAL      WORK( * )

COMPLEX   AP( * )

PURPOSE
CLANTP  returns the value of the one norm,  or the Frobenius
norm, or the  infinity norm,  or the  element of  largest
absolute value  of a triangular matrix A, supplied in packed
form.

DESCRIPTION
CLANTP returns the value

CLANTP = ( max(abs(A(i,j))), NORM = 'M' or 'm'
(
( norm1(A),         NORM = '1', 'O' or 'o'
(
( normI(A),         NORM = 'I' or 'i'
(
( normF(A),         NORM = 'F', 'f', 'E' or 'e'

where  norm1  denotes the  one norm of a matrix (maximum
column sum), normI  denotes the  infinity norm  of a matrix
(maximum row sum) and normF  denotes the  Frobenius norm of
a matrix (square root of sum of squares).  Note that
max(abs(A(i,j)))  is not a  matrix norm.

ARGUMENTS
NORM    (input) CHARACTER*1
Specifies the value to be returned in CLANTP as
described above.

UPLO    (input) CHARACTER*1
Specifies whether the matrix A is upper or lower
triangular.  = 'U':  Upper triangular
= 'L':  Lower triangular

DIAG    (input) CHARACTER*1

Specifies whether or not the matrix A is unit tri-
angular.  = 'N':  Non-unit triangular
= 'U':  Unit triangular

N       (input) INTEGER
The order of the matrix A.  N >= 0.  When N = 0,
CLANTP is set to zero.

AP      (input) COMPLEX array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed
columnwise in a linear array.  The j-th column of A
is stored in the array AP as follows: if UPLO = 'U',
AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO =
'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
Note that when DIAG = 'U', the elements of the array
AP corresponding to the diagonal elements of the
matrix A are not referenced, but are assumed to be
one.

WORK    (workspace) REAL array, dimension (LWORK),
where LWORK >= N when NORM = 'I'; otherwise, WORK is
not referenced.
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